大断面软岩隧道变形控制技术研究

隧道开挖后受地应力影响极易发生变形,严重的将导致坍方等安全事故,若侵入结构还需要二次扩挖处理。为保障软弱围岩隧道的施工安全,避免二次扩挖,结合国内外隧道的典型案例和经验,从分析围岩的强度应力比出发,针对不同的软岩类型,对预留变形量、预加固措施、弱爆破的基本原则,综合信息方法、支护措施、施工要点等内容进行归纳研究。研究表明:1)预留变形量选择要充分考虑隧道的最大地应力和不同软岩物理特性的影响;2)上台阶采取有效预加固措施后,可以实施大断面开挖;3)不同地应力环境,必须根据信息成果,针对变形特征优化设计支护参数后,变形完全能够有效控制。

Study on Deformation Control Technology for Large Cross-section Tunnel in Soft Rock

Due to the effect of ground stress, problems such as deformation, collapse and accident may occur after tunnel excavation, and secondary enlarging excavation may be needed in extreme cases. In the paper, the deformation allowance, advance reinforcement, weak blasting, comprehensive information method, support measures and key construction points for large cross section tunnels in soft rocks are summarized and studied on basis of typical work cases, so as to guarantee the construction safety of soft rock tunnels and to avoid secondary enlarging excavation. The study shows that: 1) In the determination of the deformation allowance, the maximum ground stress and the physical properties of different soft rocks should be taken into full consideration. 2) Large cross section excavation can be carried out after effective advance reinforcement of the top heading. 3) The deformation can be brought under effective control by optimizing the supporting parameters on basic of ground stress and deformation properties.